Two Mad Geeks

Besides being a shortcut way to copy cells, AutoFill can quickly create a series of incremental values. For example, if you need a list of values from 1 to 100 to appear in A1:A100, you could do it with formulas. You would enter 1 in cell A1, the formula =A1+1 into cell A2, and then copy the formula to the 98 cells below.

You could also use AutoFill to create the series for you without using a formula. To do so, enter 1 into cell A1 and 2 into cell A2. Select A1:A2 and drag the fill handle down to cell A100.

When you use AutoFill in this manner, Excel checks out the selected cells to figure out how to complete the rest of the series. If A1 contained 1 and cell A2 contained 3, Excel would recognize this pattern and fill in 5, 7, 9, and so on. This technique also works with decreasing series and dates. Excel even recognizes common series names such as months and days of the week.